This document relates to optical amplifiers and lasers.
Various optical amplifiers are designed to amplify light by providing an optical gain at the same wavelength of the light to be amplified so that the light, after transmitting through an optical gain medium of the optical amplifier, is amplified in its power or energy and the amplified light is at the same wavelength of the original light prior to the amplification. The optical gain of the optical amplifier can be obtained by pump light that optically excites the optical gain medium such as a Nd or Yb doped fiber amplifier, or by an electrically energized gain medium such as a semiconductor optical amplifier based on quantum wells and other gain mechanisms.